The discovery of a new subatomic particle that is likely the elusive Higgs boson — a particle thought to give all other matter its mass — could be an important step toward uncovering dark matter, physicists say.
In a much-hyped announcement July 4 from the world’s largest atom smasher, the Large Hadron Collider in Switzerland, scientists reported evidence of a new “Higgs-like” particle with roughly 125 times the mass of the proton.
The researchers claimed a high level of certainty that the new particle is the long-sought Higgs boson, which is thought to answer how all other matter has mass. Higgs is the missing link in the reigning theory of particle physics, known as the Standard Model, but finding the particle has even wider implications: It opens the door beyond the Standard Model for explaining the existence of dark matter, the mysterious substance widely thought to make up 83 percent of all matter in the universe.
Dark matter has yet to be directly detected; its presence is inferred based on its gravitational pull. Confirming the characteristics of the newly found Higgs-like particle could account for dark matter.
While dark matter is not explained as part of the Standard Model, evidence for the enigmatic substance (based on its gravitational effects) is hard to ignore. This could mean the Standard Model is only part of a wider framework to explain the universe, said Harvey Newman, a professor of physics at the California Institute of Technology, Pasadena.
“We can’t really deny the existence of dark matter,” Newman said. “The Higgs particle that we found doesn’t prevent us at all from searching for particles that lie beyond the Standard Model. We still need a candidate for dark matter.”
If the newfound particle is consistent with the Standard Model, physicists may be able to use these results to craft a more encompassing picture of the universe.
“You can think of what we found as the key part of the genetic blueprint of the universe,” said Maria Spiropulu, another Caltech physics professor, who was in the audience at the July 4 announcement in Switzerland.
Further experiments could indicate that the composition of dark matter requires a more fundamental explanation than the Standard Model, Newman said.
“Even if we find out that this is indeed, to the best of our ability to measure, the Standard Model Higgs boson, there are all these other questions that are unanswered,” he said. “One of the first questions is: What composes the dark matter in the universe? There’s no room in the Standard Model of the universe to make up the dark matter, so we have to look at other candidate alternatives.”
One such alternative is “supersymmetry,” an extension of the Standard Model. Supersymmetry suggests that every known elemental particle has a partner that is identical except for its spin. For instance, photons would have partner “photinos,” and electroweak bosons would have duplicate “electroweak-inos.”